Memory-Erasing Drugs

Memory-erasing drugs would be possible if forgetting were not a passive process, as it often seems to be. However, according to Yi Zhong, a neurogeneticist at Tsinghua University in Beijing and Cold Spring Harbor Laboratory in New York, there is "an active system to erase memory, completely independent from the mechanisms to form memories."

Zhong and his colleagues made their discovery by training fruit flies with two odors, one of which was paired with a foot shock to the insects as they smelled it. That experience normally leads flies to avoid the shocking odor in favor of the alternative.

In the first set of experiments, the researchers left the flies alone after their training session was over, later testing them at specific points in time as their memory weakened. In a second experiment, the researchers disrupted the odor-shock memories by exposing flies to a new pair of odors. Finally, they reversed the flies' lesson, delivering the foot shock in conjunction with the opposite odor.

In all cases, the flies forgot what they learned previously, which the researchers suspect was due to a small protein known as Rac that switched on with the passage of time. This molecule switched on faster when the insects either got distracted by new experiences or confused by conflicting information.

Philip K. Dick made excellent use of this idea. In his 1966 short story We Can Remember It For You Wholesale he writes about selectively erasing memories:

Someone, probably at a government military-sciences lab, erased his conscious memories; all he knew was that going to Mars meant something special to him, and so did being a secret agent...
(Read more about erasing memories)

Even earlier, Jack Vance wrote about the idea of "extirpating memory" in his 1956 novel To Live Forever:

"Here it is — anti-heptant. Water-soluble, non-toxic, highly effective. When it is present in the cerebral blood supply, it acts like the eraser button of a recorder, canceling whatever circuits are active, but inactive toward those not in use."
(Read more about anti-heptant)